The invention is directed to a device for the thermal treatment of bulk materials, particularly for cooling hot cement clinker emerging from a calcining furnace, comprising a materials transfer means arranged in the region under the furnace discharge that can be charged with cooling gas and comprises a stepped grate inclined relative to the horizontal, this materials transfer means being followed by a grate such as, for example, a sliding grate that carries and conveys the material to be cooled.
Devices of this species are employed in the nonmetallic minerals industry in order to highly cool the material (for example, cement clinker or other mineral materials) previously calcined in a calcining furnace immediately thereafter in the desired way. The red-hot material coming from the furnace discharge should experience an initial, great cooling in a materials transfer means that can be charged with cooling gas and leads to the actual cooler, usually a sliding grate cooler, traveling grate cooler or the like, and should thereby be conveyed with optimally good distribution to the following cooler on which the main cooling work is then performed while the material to be cooled continues to be conveyed in longitudinal direction. At least the cooling air blown through the hot material in the materials transfer means should generally be reemployed or, respectively, employed in some other way in the preceding furnace system as heated combustion air (secondary air, tertiary air).
In a known cooling means for cooling hot cement clinker (periodical "Zement-Kalk-Gips", No 2/95 pages 87-90), the materials transfer means preceding a conventional sliding grate cooler is composed of a single stepped grate chargeable with pulsating cooling air whose angle of inclination is smaller than the natural angle of slope of the hot cement clinker emerging from the calcining furnace, so that a layer of material remains lying on the stepped grate on whose surface the fresh product material to be cooled should slide in the direction to the conventional grate cooler. The fresh cement clinker bed should thereby also slide on the single slope of the materials transfer means when the bed is advanced on the following sliding grate cooler. However, one does not efficiently succeed in distributing the fresh clinker bed transversely relative to the main conveying direction as well with the known materials transfer means; this would be necessary for a good heat transfer between the hot cement clinker and the cooling air. When the sole stepped grate of the known materials transfer means is fashioned extremely long, the risk is not precluded that the fresh clinker bed can no longer maintain itself on the stepped grate, which would result in too low a clinker bed height, too short a dwell time of the cooling air in the clinker bed and the inadequate cooling thereof. Insofar as the surface of the hot, fresh clinker bed were to crust due to inadequate cooling on a zone-by-zone basis, whereby incrustations at the surface of the bulk material would impede the passage of the cooling air, then the known cooling means would make no provision therefor that such incrustations are in turn destroyed immediately after they arise insofar as possible.
An object of the invention is to create a device of the species initially cited having an improved materials transfer means that, given low technical outlay, enables an efficient distribution of material transversely relative to the conveying direction as well, enables a reliable break-up of incrustations of material potentially forming on the bed of bulk material and offers further advantages and that, finally, makes an increased heat recovery or, respectively, heat recuperation from the clinker heat back into the furnace system and, thus, a further reduction in the specific heat requirement of an overall cement clinker production line possible.